[Characteristics of amino sugar accumulation in rhizosphere and non rhizosphere soil of rice under different fertilization treatments]. / ä¸åŒæ–½è‚¥å¤„ç†ä¸‹æ°´ç¨»æ ¹é™ å’Œéžæ ¹é™ åœŸå£¤ä¸­æ°¨åŸºç³–ç§¯ç´¯ç‰¹å¾.

Soil samples were collected from paddy ecosystem under five long-term fertilization treatments, including control without fertilizer (CK), chemical fertilization alone (NPK), rice residue combined with NPK (NPKS), 30% manure plus 70% chemical fertilizer (LOM), and 60% manure plus 40% chemical fertilizer (HOM) in Ningxiang City, Hunan Province. The cha-racteristics of amino sugars accumulation in the rhizosphere and non-rhizosphere soils at rice tillering stage were analyzed. Results showed that the contents of soil organic carbon, total amino sugars and three amino monosaccharides (muramic acid, glucosamine and galactosamine) with long-term application of organic materials (rice residue or manure) were significantly higher compared with CK and NPK. The inconsistent accumulation trends of the three amino monosaccharides under different fertilization treatments indicated that different responses of microbial groups to various fertilization treatments. The content of total amino sugars was not significantly different between the rhizosphere soil and the non-rhizosphere soil, probably because the agricultural operations such as plowing could homogenize paddy soils. The contribution of amino sugar derived carbon to soil organic carbon ranged from 24.0 to 28.3 mg·g-1, which was highest in NPKS, and lowest in HOM and CK. The ratio of fungal to bacterial residues (fungal glucosamine/muramic acid) ranged from 24.4 to 36.6, indicating that fungi dominated the degradation and transformation of organic matter in all the soils. Compared with that under NPK and CK, the participation of organic matter transformation from fungi under NPKS treatment was increased, whereas the bacteria involved in organic matter transformation under HOM treatment was enhanced.

Atomic-scale magnetometry of distant nuclear spin clusters via nitrogen-vacancy spin in diamond.

The detection of single nuclear spins is an important goal in magnetic resonance spectroscopy. Optically detected magnetic resonance can detect single nuclear spins that are strongly coupled to an electron spin, but the detection of distant nuclear spins that are only weakly coupled to the electron spin has not been considered feasible. Here, using the nitrogen-vacancy centre in diamond as a model system, we numerically demonstrate that it is possible to detect two or more distant nuclear spins that are weakly coupled to a centre electron spin if these nuclear spins are strongly bonded to each other in a cluster. This cluster will stand out from other nuclear spins by virtue of characteristic oscillations imprinted onto the electron spin decoherence profile, which become pronounced under dynamical decoupling control. Under many-pulse dynamical decoupling, the centre electron spin coherence can be used to measure nuclear magnetic resonances of single molecules. This atomic-scale magnetometry should improve the performance of magnetic resonance spectroscopy for applications in chemical, biological, medical and materials research, and could also have applications in solid-state quantum computing.